Fabrication of homogenous multilayered W films by multi-step sputtering deposition: a novel grain boundary enrichment strategy

Abstract

Using a multi-step deposition approach, we develop a strategy of homogeneous multilayered (HM) structure to enrich the grain boundary (GB) of sputtered W films. In comparison with the single-layered film, the HM W film is easily controllable for the film GB density. When decreasing the film modulation period t m from 160 nm to 7 nm, the GB density gradually increased from 0.065 nm(-1) to 0.275 nm(-1) without changing the phase structure of the films. Accordingly, the film's electrical resistivity and mechanical hardness, which are related to the GBs, changed from 40.1 μΩ · cm to 75.3 μΩ · cm and from 12.1 GPa to 16.2 GPa, respectively. Detailed analysis showed that the formation of an HM structure is related to the temperature evolution of the film growing surface during the multi-step sputtering process. This study could provide a general engineering approach to enrich film interfaces and allows for the development of thin films with novel microstructures.

Effect of deposition parameters on surface roughness and consequent electromagnetic performance of capacitive RF MEMS switches: a review

“…This is consistent with the results in some papers that the surface roughness of the deposited films increases with film thickness [54,55]. Zhu et al [53] also reported that this phenomenon was related to the variation in the grain size because RMS roughness was determined by the height fluctuations in the surface profiles.…”

“…Van Zwol et al [50] found that σ RMS of Au films increased from 1.68 to 9.92 nm when t film increased from 100 to 1600 nm. As well as Au, the surface roughness of titanium (Ti) [52] and tungsten (W) [53] has also been investigated by other researchers. Table 1 lists the deposition conditions and test results in detail.…”